Flying boat hull



y 1944- K. ARNSTEIN ETAL 2,349,584

FLYING BOAT HULL Filed Aug. 24, 1940 3 Sheets-Sheet l y 1944. K.ARNSTEIN ET AL 2,349,584

. FLYING BOAT HULL Filed Aug. 24, 1940 a Sheets-Sheet 2 ZhWc Mwb Karlflf/zste in 1% May 23, 1944. ARNSTEIN ETAL 2,349,584

FLYING BOAT HULL Filed Aug. 24, 1940 s Sheets-Sheet 5 Patented May 23,1944 UNITED STATES PATENT orrics FLYING BQAT HULL Karl Arnstein, Akron,

and Benjamin J. Schnitzer,

Stow, Ohio, assignors to Wingioot Corporation,

Akron, Ohio, a

corporation of Delaware Application August 24, 1940, Serial No. 354,056a v 11 Claims.

. structure against injurious impact forces in the water. I

It has been customary to build the hulls of flying boats entirely rigidof materials such as either metal or wood. The landing shocks to whichsuch boats are subjected are occasionally extremely severe and,therefore, the hull, as well as the remaining structure, including thewings, must be made correspondingly strong and heavy. However, even thenhull injuries frequently occur. It is known that successful use ofpneumatic floats, constructed of flexible material, has been made forhydroplanes. It is also-knwn that designs exist'which suggest a flyingboat hull constructed entirely or partially as an inflatable hollow bodywhich is stiffened by pressure from the inside. Such designs, however,have not been proven practicable for various reasons.

This invention overcomes the above-mentioned deficiency by employing arather conventional hull construction in combination with a resilientlanding cushion which is attached underneath the bottom of' the rigidhull structure. By this method not only the landing shocks are dampened,but it also quickens a take-off of the. flying boat, due to theadaptability of the soft cushion to bring about a smoother flow of thewater. Such an arrangement of the shock-absorbing portion of the hullhas the advantage that full use can be made of the space within the hullstructure for operation, storage, etc. purposes without any interferenceby the shock absorber. The size and construction of the landing cushionmay be varied to a great extent, according to requirements.

The bottom of the hull is usually provided with a. step to avoid suctionwhile getting oil the water. With a hull being provided with acushnumerable little gas cells entirely separated from each other byvery thin rubber walls. The advantage of employing a cushion underneatha flying boat hull does not lie only in the protection of th structuralparts against hard impacts, but also in the fact thatthe entire boatstructure .can be carried out lighter in weight,

ion the step can be easily formed by a cushion which covers onlythefront portion of. the hull bottom to be immersed, or a cushion may beemployed containing the step and extending over the full length of thathull portion. The width of the cushion may correspond to that of thebottom of the hull or may extend over only a portion of it. 1

So far as the construction of the landing cushion, according to thisinvention, is concerned,

it can be of the inflatable pneumatic type or the air inflatable spacecan be displaced by light-weight rubber foam which consists of inthisresulting in greaterefficiency and better performance of the aircraft.In using the pneu' matic-type cushion, the step whichis of advantage foran easier take-off, may be made to disappear partly or entirely byreleasing some of the air in the cushion poriton in front of the stepwhen out of the water, thus reducing the airre-- sistance of the boat inflight.

For a better understanding of this invention, reference is now made tothe accompanying drawings wherein several embodiments are shown merelyby-way of illustration, and where Fig. 1 is a side view of one form offlying boat embodying the invention;

Fig. 2 is a bottom view of Fig. 1;

Fig. 3 a front view thereof;

Fig. 4 is a cross-sectional view on an enlarged scale taken on line 4-4of Fig. 1;

Fig. 5 is one modification of the construction shown in Fig. 4;

Figs. 6, 7 and 8 are views similar to Figs. 1, 2 and 3, respectively,showing another modification of the invention;

Fig. 9 -is a fragmentary longitudinal sectional View, in enlarged scale,showing the step portion of the landing cushion;

Fig. 10 is a cross-section,' in enlarged scale, along the line Ill-l0 ofF156;

Fig. 11 is a modification of the construction shown in Fig. 10;

Figs. 12 and 13 are further modifications of the construction shown inFig. 10; and

Fig. 14 is a modification of the constructions shown in Figs. 4 and 5.

In the drawings the same numerals are used for identifying correspondingparts throughout the different views.

Referring first to Figs. 1 to 4 inclusive, it will be seen that theflying boat therein shown has a rigid hull II which is provided at itsfront portion underneath the bottom with a landing cushion l2, includinga number of flexible air tubes l3 of substantially equal diameter. Thesetubes, which are arranged longitudinally and substantially parallel toeach other, are enclosed by a cover M which is fastened along its edgesl5 by a metal strip l6 and bolts I! to the rigid hull, and are-cementedto the cover by fabric angle strips I8 to prevent dislocation. Some orall of these tubes may be provided with bolts l9 securely embedded withtheir heads in the tube walls and to be fastened to the bottom'of thehull. Chafing injuries during service.

, to accomplish an easy take-off from the water. The material used forthe tubes, as well as for the cover, is water-proof and is preferablyrubberized fabric composed of one or more plies, depending on theservice it has to perform. Each one of the tubes I3 is equipped withan'air inflation valve 23. The valves of symmetrically located tubes areconnected in pairs by hose 24, from each of which leads a line attachedto an air manifold 26 which is provided with a stop it valve 21 for eachline 24. A main line 28 feeds the air from a tank 2!! to the manifold26. Although the operating pressure in the tubes is relatively low, eachpair of tubes is also equipped with a safety valve 30, set to blow offat a prede- 20 termined pressure. This pressure might be exceeded whenthe, flying boat reaches high altitudes, whereby the pressuredifference. between inside the tubes and the outside atmosphereconsiderably increases. There also is provided a 2:! pressure gauge 3|connected to a manifold 32 into which a line 33 leads from each pair ofair cover under sufiicient tension for keeping the tubes in thecorrugations. Otherwise, the con- 0 struction is substantially the sameas that described in reference to Fig.4.

Another modification of the above-described construction of the landingcushion is shown in Figs. 6 to 10. The cushion in this constructionextends over the full length'of the hull bottom, that is, so far as itimmerses in the water, and

is of considerably greater height, thus securing a softer impact and abetter protection of the rigid hull structure. The bottom of the hull His shown straight in the cross-section and the keellike. shape isproduced entirely by the landing cushion 4|, which also contains thestep 42. The air tubes l3, arranged again substantially parallel to eachother, are of. different diameter decreasing from the center outwardly.Each tube is fastened by bolts I9 to the bottom of the hull to be heldin place. The cover I4, which is fastened by metal strips l6 and boltsI! along its edges Hi to the rigid hull, encloses the air tubes of whichthose of the front portion of the cushion are of larger diameter thanthose of the rear portion. A transverse wall 43 is inserted between thefront and rear tubes for the purpose ofshaping the step. Chafing stripsor moldings 20 and 2|, preferably made of rubber, for protecting thecushion are also provided, and the cover I4 is .attached by fabric anglestrips l8 to the air tubes.

In case the disappearance ofthe step is desired during flight, the outercover portion 42 is made of resilient material which, when some of theair in the front tubes is released, will contract and smooth outsomewhat, or substantially eliminate the step as shown in dotted lines,and thus reduce the air resistance during flight. In doing that,

some of the air is released from the front tubes; the inside pressur mayeven be reduced below that of the atmosphere.

This very same construction is shown, somewhat modified, in Fig. 11.Here, each air tube has on top a longitudinal indentation of triangularcross-section into which fits a girder fastened to and supporting thetube. This way, the tubes are held much firmer at the base againstyielding laterally. With this arrangement there is also the possibilityof avoiding use of the outer bottom cover of the rigid hull structure,except, perhaps of a small width 46 which braces the outer wall of thehull against the adjacent triangular girder. I

Figures 12, 13 and 14 show modifications of the cushion construction ofFig. 10. In these views the landing cushion consists of two enclosingwalls 48 and 49, as well as of partition walls 50, cemented by anglestrips 5| to the enclosing walls and thus divide the cushion into anumber of separate air chambers, all of which are inflated withcompressed air. In Fig. 12, the partition walls are arranged in zig-zagfashion giving the air chambers a triangular cross-section, whereas inFig. 13 the partition walls are more or less parallel to each other andform, together with the outer walls, air chambers of substantiallyheight. This construction may be found most effective, particularly incases where a relatively short type landing cushion is used.

The above-detailed description of this invention, it is believed, willgive a clear conception of the advantage of the new featuresincorporated therein over previous constructions. However, it should beunderstood that the examples illustrated and described do by no meansexhaust the possibilities of the invention, but that many othercombinations and variations therefrom might be included which fallwithin the, spirit and scope of this invention, as defined by theattached claims.

We claim: I

1. In combination in a flying boat, a rigid hull structure, a resilientlanding cushion underneath and fastened to said rigid hull, said landingcushion comprising a plurality of longitudinal flexible inflatable tubessubstantially parallel to each other, a step dividing said landingcushion into a front portion and a rear portion, the inflatable tubes insaid front'portion as well as in said rear portion decreasing indiameters from the longi- 5 tudinal center toward the sides of the hull,the

tubes in the front portion being larger in diameter than correspondingtubes in the rear portion, fastening means for attachingsaid tubes tothe bottom of said rigid hull, an airtight and waterproof flexible coverenclosing said tubes being attached and sealed to th bottom of saidrigid hull, means for attaching said cover to the bottoms of said tubes,and chafing strips longitudinal of and fixed to the outer surface ofsaid cover for protection.

2. In combination in a flying boat, a rigid hull structure having alongitudinally upwardly curved bottom, front and rear, a resilientlanding cushion attached to the bottom of said hull, said cushioncomprising two groups of air containers, 8. front group and a reargroup, composed of flexible but non-stretchable air-tight and waterprooffabric, andadapted to be inflated with air usually at super-atmosphericpressure, the front group being of greater height than th rear groupadjacent thereto, each of said groups being enclosed by an air-tightflexible cover, which is fastened and sealed along the bottom of saidrigid hull, and 'a resilient air-tight connection'forming a step betweensaid front and rear covers, which, when the air pressure in said frontcontainers is reduced during flight, will contract and thus reduce theheight of the step between the two groups of con-' tainers and,correspondingly, the air resistance of said step.

3. In combination in a flying boat, a rigid hull structure havinglongitudinally an upwardly curved bottom, front and rear, a resilientinflatable landing cushion fltted and attached to said bottom, the frontportion of said cushion being of greater length and of greater heightthan its rear portion, thus forming a step between the two portions, thewidth of the front portion of said cush-' ion being substantially thesame as that of the bottom of the rigid hull and the width of the rearportion diminishing rearwardly from said step to give streamline eflect.

4. In combination in a flying boat, a rigid hull structure, anair-inflatable landing cushion mounted below said rigid hull andconsisting of an upper flexible wall and of a lower flexible wall spacedfrom each other, said upper wall resting against the bottom of the rigidhull, longitudinally disposed flexible partitions spaced from each otherand connecting said walls to divide the landing cushion in a pluralityof individual air-tight to provide a stable lateral support for saidtubes,

- and an outer flexible cover having its edges secured compartments,said compartments decreasing in I cross-sectional height from thelongitudinal center toward the sides of the hull and valves inserted inthe enclosing wall for inflating said compartments with air.

5. In combination in a flying boat, a rigid hull structure, aninflatable landing cushion mounted underneath said rigid hull andconsisting of an upper flexible wall and of a lower flexible'wall, bothcombining to form an air-tight bag, said upper wall resting against thebottom of said rigid structure, longitudinal flexible partitionsarranged transversely inzig-zag fashion and being connected to saidupper and said lower wall to divide the landing cushion in a pluralityof individual air-tight compartments, said compartments decreasing incross-sectional height from the longitudinal center toward the sides ofthe hull and valves inserted in the enclosing wall for inflating saidcompartments with air.

6. In a flying boat, the combination of a hull of rigid construction anda resilient landing cushion underneath the bottom of said hull, saidcushion comprising a plurality of separate inflatable air tubes, each ofwhich has on top a longitudinal indentation, a corresponding number ofgirders fltting into said indentations and secured to the bottom of saidhull toprovide stable lateral support for said tubes, and an outerflexible cover having its edges securedto said rigid hull and providinga smooth air-tight enclosure of said air tubes.

7. In a flying boat, the combination of a hull of rigid construction anda resilient landing cushion underneath the bottom of said hull, saidcushion comprising a plurality of separately inflatable air tubesarranged longitudinally, said tubes decreasing in diameters from thelongitudinal center toward the sides of the hull, and each of the tubeshaving on top a longitudinal indentation, a corresponding number ofgirders fitting into said indentations and secured to the bottom of saidhull to said rigid hull and providin a smooth, airtight enclosure ofsaid air tubes.

8. In a flying boat, the combination of a hull of rigid construction anda resilient landing cushion underneath the bottom of said hull', saidcushion comprising a plurality of longitudinal separately inflatable airtubes substantially parallel to each other, a step dividing the landingcushion into a front portion and a rear portion, the tubes in the frontportion being larger in diameter than corresponding tubes in the rearportion and each having on top a longitudinal indentation, acorresponding number of girders fitting into said indentations andsecured to the bottom of said hill] to provide a stable lateral supportfor said tubes, and an outer flexible cover having its edges secured tosaid rigid hull and'providing a smooth, air-tight enclosure of said airtubes.

9. In a flying boat, the combination of a hull of rigid construction anda resilient landing cushion underneath the bottom of said hull, saidcushion comprising a plurality of longitudinal separately inflatable airtubes substantially parallel to each other, a step dividing the landingcushion into a front portion and a rear portion, the tubes in said frontportion being larger in diameter than corresponding tubes in the rearportion and each having on top a longitudinal indentation, a.corresponding number of girders fitting into said indentations andsecured to the bottom of said bull to provide a stable lateral supportfor said tubes, and an outer flexible cover having its edges secured tosaid rigid hull and providing a smooth, air-tight enclosure oi said airtubes, the width of the front portion of said cushion beingsubstantially the same as that of the bottom of the rigid hull and thewidth of the rear portion diminishing rearwardly from said step to givestreamline effect.

10. In a flying boat, the combination of a hull of rigid constructionand a resilient landing cushion underneath the bottom of said hull, saidcushion comprising a plurality of separate inflatable air tubes, each ofwhich has on top a longitudinal indentation, a corresponding number ofgirders fitting into said indentations and secured to the bottom of saidhull to provide a stable lateral support for said tubes,'and an outerflexible cover having its edges secured to said rigid hull and providinga smooth, air-tight'enclosure of said air tubes, said outer flexiblecover aswell as the air tubes being formed of treated fabric andassembled in streamlin form.

ll. In a flyingboat, the combination of a hull of rigid construction anda resilient landing cushion underneath the bottom of said hull, saidcushion comprising a plurality of separate inflatable air tubes, each ofwhich has on top a longitudinal indentation, a corresponding number ofgirders fitting into said indentations and secured to the bottom of saidhull to provide a stable lateral sup- 'port for said tubes, an outerflexible cover having its edges secured to said rigid hull and providinga smooth, air-tight enclosure of said air tubes, said outer flexiblecover as well as the air tubes being formed of treated fabric andassembled in streamline form, and flexible chafing strips longitudinalof and fixed to the outer surface of said cover for protection.

KARL ARNSTEIN. BENJAMIN J. SCHNITZER.

